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[Articles Home]  [Add Article]  

EMT Vertical

Marcos Antonio Veloz Burgos (HI8MVW) on June 26, 2010
View comments about this article!

Some time back I wrote a short article on my then PVC PIPETENNA, and the reaction to it was satisfying to me.

I took down that little antenna and came up with something more practical and effective, a quarter- wave vertical made of EMT tubing (available the world over) for the 20 meter band that works also on 15 meters without an antenna tuner, and has an acceptable SWR on 10, 12 and 17 meters using a tuner.

Go ahead you puritans and call me crazy, but am using high quality RG-6 cable with this antenna and it works fine, a 1:1 on 14MHZ and 1.25:1 on 21MHZ...jojo.

Radio Shack carries an adapter F to PL259. Am having fun with this antenna and if you fellows just follow the plan attached, you will be part on my fun world after you make contacts with Moscow, Central Africa or Buenos Aires.

As with any antenna, this one must be mounted clear of any structure or objects that may cause interference.

Any problems? My e-mail is at QRZ.COM.

From sunny Santo Domingo, Dominican Republic,

73 Marcos - HI8MVW

Member Comments:
This article has expired. No more comments may be added.
 
EMT Vertical  
by KH6DC on June 26, 2010 Mail this to a friend!
Marcos,

Great looking antenna and simple to build. That's on my next "build" list.

73 and thank you,

Delwyn, KH6DC
Honolulu, Hawaii, USA
 
EMT Vertical  
by KE5KDT on June 27, 2010 Mail this to a friend!
Great inexpensive antenna that could be built for just about any freq. Your use of 75 ohm cable has given me the idea of using my unused TV cable input on the other side of the house to hook up to a ham antenna and then connect up a low power hf unit from any room in the house. I realize it is not the same as a single run of coax, but what the heck, ham radio is about experimenting just like you did with your electrical conduit antenna. Thanks, much appreciated.
73s Bob KE5KDT
 
RE: EMT Vertical  
by K3MRK on June 27, 2010 Mail this to a friend!
check the band width on your splitter might cut off at 25 mhz
 
RE: EMT Vertical  
by AE6RO on June 27, 2010 Mail this to a friend!
1). What if you don't know how to weld?

2). A little bit sobrepeso.

3). In this time of the Solar Minimum, a vertical may not be enough. However, the author's call ought to be worth at least 10 db! 73, Juanito
 
EMT Vertical  
by WA8QNN on June 27, 2010 Mail this to a friend!
I've made several antennas with EMT conduit over the years the stuff works great. I've used a piece of pvc conduit as an insulating sleeve over the EMT for support.
I've worked in the electrical trade for 35 years, don't stop using emt just for antennas you can make all kinds of stuff with this. Some real nice bike racks were made with EMT.
Besides duct tape and velcro EMT is one of man's greatest inventions.
Let your creativity run wild.

Larry
WA8QNN
 
RE: EMT Vertical  
by KN9D on June 28, 2010 Mail this to a friend!
If you can't weld or have a friend weld ,then just use a stain;ess steel hose clamp.

Or you could drill a small hole for a stainless steel 8-32 machine screw and fasten the inner conductor with a washer or two.

Theoretically there will be a 2:1 mismatch between a 75 ohm coax and a quarter-wave vertical working against an excellent ground;in the real world additional ground losses will actually lower the mismatch at the cost of some signal being wasted.

Actually getting on the air with a 50% efficient vertical sure beats staying off the air waiting to install that perfect antenna.

Besides,many hams proudly brag of the contacts made using their mobile antennas which are much less than 50% efficient.

Good job, Marcos!
 
RE: EMT Vertical  
by HI8MVW on June 28, 2010 Mail this to a friend!
Dear Mr. Menne: If the radials are mounted on a horizontal way, there will be about 37 ohms a the feet point, in my case the radials drop down almost vertically and that brings the feetpoint Z up close to the RG-6 cable 75 ohms.

Thanks amigo, 73, Marcos
 
EMT Vertical  
by KB4WEC on June 28, 2010 Mail this to a friend!
I built something very close to this about a year ago using type 'L" copper tubing. top section was 1/2" o.d. and the bottom was 3/4"o.d. Use small L.P. gas tourch and 95/5 solder, attach the coax with a stainless steel hose clamp, cover with caulk, I've got 8 wire radials about 17 feet long each. Antenna is mounted on top of garage base is about 18ft above grade. Works great on 20, and I use a small tuner for all bands above 20. Have worked all over Europe and South America with 100 watt and less.
More guy's need to get of the but_ and build things, that's a big part of our ham radion history.
73,
Bob
KB4WEC
 
EMT Vertical  
by W5LZ on June 28, 2010 Mail this to a friend!
"Go ahead you puritans and call me crazy..."
Okay, you're crazy. But if it works, it works. Good!
Paul
 
RE: EMT Vertical  
by N9AOP on June 29, 2010 Mail this to a friend!
About 30 years ago Ham Radio Horizons had an article about constructing an 80 meter top hat vertical. I used 3 sticks of 1/2 emt and electric fence wire for the capacitative hat. Looking back in my log I find that that antenna worked quite well and gave me WAC on 80m. EMT is cheap, available anywhere and I guess that is what makes it fun to experiment with.
Art
 
RE: EMT Vertical  
by K1BXI on June 29, 2010 Mail this to a friend!
You know those pesky electrons whack their neighbors easier in aluminum than steel, so any performance difference between steel EMT and one made with aluminum conduit?

John



 
RE: EMT Vertical  
by AE5NE on June 29, 2010 Mail this to a friend!
KE5KDT:

Go ahead and try it, but the arbitrary length stubs of coax (open at the far end) will look like a "short" if they are an odd multiple of 1/4 wavelength on your chosen frequency.

In other words, if you have RG-6 with 74% velocity factor, and one of those coax runs happens to be 13 feet, it will short out your transmitter somewhere right in the middle of the 40m band.

If you have an an antenna analyzer it would be interesting to frequency sweep it.

Joe AE5NE




 
RE: EMT Vertical  
by AE5NE on June 29, 2010 Mail this to a friend!
Er, I meant the 20m band for a 13ft RG-6 stub.
 
RE: EMT Vertical  
by K5QED on June 30, 2010 Mail this to a friend!
A good article, and proof that an effective antenna does not have to be something purchased for a high price.

A few years back, I built a similar 1/4-wave vertical for 17m out of a couple of lengths of copper pipe topped by a steel CB whip antenna. The radials were lengths of copper 14 GA house wire, and the antenna was mounted on the roof at only 15' or so.

It worked well where I lived in Texas, where the ground conductivity was fairly decent, and I made some great DX contacts using only 100W.

The biggest advanage was probably the lower takeoff angle compared to a dipole at similar height.

I also had fun modelling the antenna with EZNEC and experimenting with parallel coupled elements for other bands.

Now I am not attempting to define the performance of the antenna by the number of contacts made, etc. but it was cheap, effective and a lot of fun.

Although copper pipe is more expensive than EMT, it can be soldered, and there are all kinds of adapters, reducers, caps and miscellaneous parts available off the shelf at your local home improvement store to complete your design.

K5QED

 
RE: EMT Vertical  
by K0FF on June 30, 2010 Mail this to a friend!
Hi Marcos and thanks for writing the article.

Good point about the 75 Ohm cable! There is nothing magic about 50 Ohm coax. I use a lot of 75 Ohm coax in my station.

Geo>K0FF
 
RE: EMT Vertical  
by KE5KDT on June 30, 2010 Mail this to a friend!
AE5NE Wrote:

"Go ahead and try it, but the arbitrary length stubs of coax (open at the far end) will look like a "short" if they are an odd multiple of 1/4 wavelength on your chosen frequency.

In other words, if you have RG-6 with 74% velocity factor, and one of those coax runs happens to be 13 feet, it will short out your transmitter somewhere right in the middle of the 40m (20)band. "

Thanks Joe (AE5NE) for the tip. I hate it when reality gets tangled up with a good idea, especially if it is going to cost me money.
Bob
 
EMT Vertical  
by K3RMX on June 30, 2010 Mail this to a friend!
Maybe I'm just having a "senior moment" but I do not understand the feedline connection process. Are the bottom 12" of mast covered with tape just to insulate the four radials from the mast, or should the radials be insulated except for the connection to the feedline braid, and the tape is wrapped over both the bottom of the mast and the radials? If the radials are insulated except at the connection point, why have the tape at all? If the tape is just to support the insulated radials, is the length of the support, i.e., 12", the least bit critical, or would just a few inches of support tape suffice?

Again, sorry for my clouded thought process today.

Steve
k3rmx
 
RE: EMT Vertical  
by HI8MVW on July 1, 2010 Mail this to a friend!

Steve:

The idea of having the 12" wrapped on tape is just to avoid the radials or even the U-bolts making electrical contact with the antenna. Also, the 12" portion serves as a support with the U-bolts holding it to the wood. Once the 12" part is insulated with tape, you may go ahead and attach the radials, holding then to the tubing using some turns of thick wire.

73, Marcos - HI8MVW
 
RE: EMT Vertical  
by KF5AHV on July 2, 2010 Mail this to a friend!
this is a nice article. i was thinking of making the same antenna except using an old 5/8 wave cb groundplane. it seems so easy yet i've never worked anybody running one. i actually hear very few 20 meter verticals unless there the commercial mulitband type.
 
EMT Vertical  
by W4HKL on July 2, 2010 Mail this to a friend!
Nice article!

Actually, I've been thinking about feeding a roof-mounted vertical of approx 18 feet tall with a remote antenna tuner (SGC, Icom, Alinco, etc) and using a few radials each for 20 thru 10 meters. The dimensions for the author's antenna was very close so it caught my attention right away.

I found some take-off angle plots for half wave (10 meters) and quarter wave verticals (20 meters)and they looked pretty good. I figure the remote tuner can "fill in the gaps" on 17, 15, and 12 meters... maybe even "good enough" on 6 meters.

I am using a Half wave end fed Inverted L on 80 - 10 (fed with an alinco remote tuner) now for all bands, and figure the second antenna would do a lot better on the higher frequencies. If I use a 9 foot CB whip for the top 9 feet and EMT for the bottom of the antenna, then it should be fairly unobtrusive, have a super-low wind load, and be easy to mount.

I noticed the dimensions for HI8MVW's antenna are about what I would use. On his QRZ page he states he's feeding it with coax, but I'd opt for the more expensive route and match it with a remote tuner and feed that with some LMR400 to reduce coax losses to the bare minimum. When all you run is 100 watts, you want as much as you possibly can to radiate from the antenna... not get "lost" in the coax.

Looking forward to hearing reports on this set up...

Steve, W4HKL
 
EMT Vertical  
by KB5ZXM on July 2, 2010 Mail this to a friend!
If one were to crimp a long 3/8 / 24 tpi stainless bolt in side of the top most piece of EMT with the threads protruding , one could use his Hustler type loading coils, that are usually just in the way. Perhaps Even a bracket that allows for three of them is avail.
I have found that the top rail of a Hurricane Type Fence , is strong, comes in 20 and 30 ft lengths and is factory wedged, and galvanized.

Small welders are cheep and can be rented. or loaned out to friends in exchange for help on other projects.
Kind of like having/playing a Bass Guitar, free beer where ever you go.
If One were so inclined.ie a Junque Yard Canine
 
RE: EMT Vertical  
by KL7IPV on July 3, 2010 Mail this to a friend!
In the "olden days" of the 60s I used EMT a lot. I built a 10 meter dipole " armstrong turned beam" from it and it worked very well. Using RG-6 coax is cheap and gives you about a 1.5:1 SWR when fed into a 50 antenna. Any turner worth anything will take that out easily.

If you cannot weld, buy two sizes of the EMT so they slide together. Slit the top of the larger size and slid the smaller into that. Use a hose clamp to tighten them together. Then you can side it in and out to adjust the SWR to where it should be. Good stuff to work with: light, easily available and cuts easy too.
Thanks for the reminder.
Frank
 
ADI AR- 247  
by KD6HVJ on July 3, 2010 Mail this to a friend!
HI does anyone know what mics i can use with this radio ? i,ve been trying to fine a stock mic MY CORD IS FALLING APART does any other brand will work with a key pad ?? eight pin? plus the display come,s on and off fred
 
RE: ADI AR- 247  
by KL7IPV on July 4, 2010 Mail this to a friend!
What model radio? Can't you find a shielded audio cord with enough wires in it to rewire the mike you have?
Frank
 
EMT Vertical  
by KJ4NOO on July 5, 2010 Mail this to a friend!
Well I built this today and so far I've worked 5 states and Ireland with great signal reports ! That is with it only 20' high for testing ! I'll have less than $10 including paint in the antenna.
 
RE: EMT Vertical  
by HI8MVW on July 6, 2010 Mail this to a friend!

Delwyn, KH6DC:

You ain't seen nothing yet, am saving the best for last. My next project will be (as soon as I get my hands on some 50foot high support) a three elements yagi using the same principles and materials...jojo.

73 to ya all from sunny Santo Domingo, Marcos


 
RE: EMT Vertical  
by WX9DX on July 6, 2010 Mail this to a friend!
I have got to ask since there are some EMT folks on this forum. What is the best way to weld this pipe? I have as several have stated built all kinds of things from EMT. But it sure would be great if I could figure out a nice way to weld it. The 100 amp stick is just not working for me and the EMT is I believe toxic???

I do have a pair of phased verticals using TV pushup poles that are really just emt in a different shape and size! :)

Jimmy, WX9DX :)
 
RE: EMT Vertical  
by WD6GLA on July 6, 2010 Mail this to a friend!
Jimmie ,

Welding any thin metal is difficult with a stick welder unless you are really good at it and have the right rod . A mig is a better way and the best way in my opinion is to braze the sections together with an oxy/acet rig

Yes the fumes are dangerous in a closed environment , but with good ventilation there is no problem and not a worry . I'm not sure what the coating is , maybe some form of galvanizing and NOT good to breath the fumes in large amounts . The stuff can make you sick or kill you but not on a small project like this and common sense used.

Marco great article, I've built a few of these things or similar and they work GREAT , dirt cheap , and easily modified . Loading coils , cap hats and all sorts of things can be done . Nice thing is if it doesnt work as planned you arent out a lot of money and in the process you learn a lot . Take it apart and try something different with the materials . Every good ham that likes to experiment should have some lengths of EMT laying around for antenna projects .

N7BDY Bob
 
RE: EMT Vertical  
by K7UA on July 8, 2010 Mail this to a friend!
A long time ago when I was in college I had an old NCX3 transceiver that only worked 80-40-20M. For antennas at my apartment 80M was out of the question space wise, but I had a wire for 40M and an EMT ground plane mounted on the roof for 20M. Being up in the clear, it worked very well with radials just lying on the roof. I ran the xcvr barefoot for a while and then added a SB200 amp for about 600-700 watts out. With the higher power I worked a lot of DX with the EMT ground plane. 73, K7UA
 
EMT Vertical  
by WA1UFO on July 10, 2010 Mail this to a friend!
Thanks Marcos for the plans!!73s de Hans in New Hampshire
 
RE: EMT Vertical  
by HI8MVW on July 12, 2010 Mail this to a friend!

Anyone with problems to clearly see the above image, just go to my page at QRZ.COM, there is the same image with a better resolution.

God bless you all and 73, Marcos
 
RE: EMT Vertical  
by VE3FMC on July 16, 2010 Mail this to a friend!
I built a 12 M vertical out of an aluminum golf ball retriever. Hung it from a branch in the maple tree in the winter so it was up off the snow. Attached 6 radials and proceeded to work a DX island on that band. I could not even copy the station on a G5RV with the apex at 20 feet.

Yet that simple vertical did the trick while hanging from the maple tree :)
 
RE: EMT Vertical  
by KN9D on July 20, 2010 Mail this to a friend!
Probably those inexpensive wire-feed light-duty welders would do for this tubing.
Fumes from the galvanizing should be NOT considered lightly;be sure to have something like a box fan nearby and stand so the fumes are being blown away from you.There is no sense in inhaling any amount of poisonous vapors.

The welding destroys the rust protection so be sure to paint or use cold galvanizing to restore the coating.

Mechanical clamping may be much simpler and cheaper for the avarage person.

Where does one buy hurricane fence tubing in 30 feet lengths? Is this only available in the Gulf area? Home supply stores here have 20 or 21 foot lengths of chain-link fence top rail and also water pipe and black iron pipe. Haven't seen 30 foot pieces.

Old RADIO magazines from the 1930s have simple rugged designs;does anyone know if those are on-line anywhere?

One RADIO article illustrated a push-up mast:bury a modest-sized pipe 5 feet or so in a concrete-filled posthole,then insert a smaller diameter 21 foot length into that and yet a third pipe inside the second.Be sure to keep about 5 feet of each inside the larger.Have boltholes drilled and bolts ready to insert to hold each upper piece in place as it is raised.Two persons working from tall stepladders could thus raise a sturdy mast to 35 or 45 feet.Just be sure you can lift the weight of the pipes and any antenna wires pre-attached.And be careful to wear good gloves because the point where one pipe slides into the next is a dangerous pincn point that can take a lot of skin or even a finger.
There are lots of good articles on simple effective antennas.
Lots of hams in the 1950 and 60s were happy just to get a 2 or 3 element beam 35 feet high or so.Just getting above the house roofs and power lines will help the signal.And a 35 foot small set doesn't catch the neighbors attention like a 70 foot tower with stacked beams.
 
RE: EMT Vertical  
by K3RMX on July 20, 2010 Mail this to a friend!
Marcos,

Thank you for your reply to my question. You cleared the fog out of my head.

I will give the antenna a try.

73,

Steve
k3rmx
 
RE: EMT Vertical  
by KJ4SEI on August 10, 2010 Mail this to a friend!
After talking to one of the certified aircraft welders here at Fred Ex I am not going to be found welding on EMT. He had a friend and fellow blacksmith die from breathing the fumes in an open vented blacksmith shop two days after he had breathed the fumes. Bolt it or clamp it but DON'T breathe those zinc fumes. If you must, clean ALL the zinc galvanizing off first.
 
RE: EMT Vertical  
by AF6IT on August 11, 2010 Mail this to a friend!
I use a pair of 19' EMT masts on top of my house guyed only at the top to support my doublet. Used 3/4" & 1" EMT. Found that when winds increase much above 50 mph the center between sections ought to be guyed as well- although since repairs cost under $5 who cares? I've considered a vertical for 80m or 40m, and I suppose if guyed well enough it could work. Just having too much fun with wire to get around to it... Yes, EMT is as FUN to play with as PVC! Tinker toys for adults!
 
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